免疫毒素的抗肿瘤研究

免疫毒素是由具有导向能力的载体（抗体或细胞因子）和具有细胞毒性的分子（毒素）偶联而成的具有特异性细胞杀伤能力的杂合分子,是一种靶向药物。免疫毒素首先利用肿瘤细胞上导向分子的受体与细胞结合,然后进入细胞,再由毒素发挥蛋白质合成抑制作用,最终导致靶细胞死亡。与其他抗肿瘤药物相比,免疫毒素具有毒性强和特异性高的优点,在肿瘤治疗中显示出巨大的应用前景。简要概述了免疫毒素的作用机理、制备及其抗肿瘤研究进展。     

Effects of umbilical cord blood stem cells on healing factors for diabetic foot injuries

The use of stem or progenitor cells from bone marrow, or peripheral or umbilical cord blood is becoming more common for treatment of diabetic foot problems. These cells promote neovascularization by angiogenic factors and they promote epithelium formation by stimulating cell replication and migration under certain pathological conditions. We investigated the role of CD34 + stem cells from human umbilical cord blood in wound healing using a rat model. Rats were randomly divided into a control group and two groups with diabetes induced by a single dose of 55 mg/kg intraperitoneal streptozocin. Scarred areas 5 mm in diameter were created on the feet of all rats. The diabetic rats constituted the diabetes control group and a diabetes + stem cell group with local injection into the wound site of 0.5 × 106 CD34 + stem cells from human umbilical cord blood. The newly formed skin in the foot wounds following CD34 + stem cell treatment showed significantly improvement by immunohistochemistry and TUNEL staining, and were closer to the wound healing of the control group than the untreated diabetic animals. The increase in FGF expression that accompanied the local injection of CD34 + stem cells indicates that FGF stimulation helped prevent apoptosis. Our findings suggest a promising new treatment approach to diabetic wound healing.     

Initial verification of the resistance management strategy for Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) in Australia

Shortly after the initial detection of western flower thrips (WFT), Frankiniella occidentalis (Pergande), in Australia during 1993 a resistance management strategy based on the alternation of chemical groups was implemented. This study aimed to verify this strategy by field testing α-cypermethrin against WFT with and without chemical alternation. Up to 114 times α-cypermethrin resistance (at LC50) was detected and resistance increased with and without chemical alternation; however, chemical alternation did significantly reduce numbers of thrips compared with a nonalternation strategy. Resistance has the potential to undermine the sustainable use of those chemicals to which there is no current detectable resistance. Consequently, chemicals with a high frequency and level of resistance against WFT need to be identified through monitoring and quickly eliminated from WFT chemical control recommendations.     

焕镛木花部数量变异和腋生花现象

对广西环江木论的焕镛木[Woonyoungia septentrionalis(Dandy)Law]自然居群花朵着生方式和性别比例作了随机抽样调查,首次发现其花的着生方式除多数为顶生花外,还有少量的腋生花,自然居群中雄株与雌株的性别比例为1.21:1,对中国科学院华南植物园栽培居群和广西环江木论自然居群20株600朵花进行的解剖统计揭示,雌、雄花各部分的数量是变化的,雄花的花被片一轮或两轮,2－6片,雄蕊81－152枚,雌花的花被片两轮,外轮2－4片,内轮4－13片,心皮3－8枚,只有雄花花药2室及雌花每心皮具2个胚珠是稳定的。花部表型性状的大幅度变异表明焕镛木具有较丰富的遗传多样性。讨论了生花与顶生花在木兰科系统发育中的意义、表型性状的异步进化现象以及建立焕镛木属Woonyoungia Law的依据。     

Effects of strobilurin containing fungicides on the deoxynivalenol content in winter wheat

The effects of the strobilurin fungicides Juwel, Juwel Top and Amistar on the deoxynivalenol contamination of winter wheat was studied in field experiments. In general, the application of strobilurins during stem elongation and inflorescence emergence of wheat resulted in increased deoxynivalenol contents in kernels as compared with the untreated control. This stimulating effect can be reversed by a following azole fungicide applied within a time period of one week during the stages of flowering.     

长江中下游湿地大型水鸟种群动态和幼鸟比例研究

迁徙水鸟保护对生物多样性保护具有重要意义。开展水鸟种群数量和幼鸟比例监测,对科学评估其种群变化趋势、制定长期保护策略具有重要价值。长江中下游湿地是东亚-澳大利西亚迁徙路线上重要的水鸟越冬区之一。本研究采用野外同步调查等方法对该区域87个湿地的亟需保护和具有代表性的10种大型越冬水鸟,其中雁形目6种,分别是鸿雁Anser cygnoides、豆雁A.fabalis、灰雁A.grus、白额雁A.albifrons、小白额雁A.erythropus和小天鹅Cygnus columbianus;鹤形目4种,分别是白鹤Leucogeranus leucogeranus、白枕鹤Antigone vipio、灰鹤Grus grus和白头鹤G.monacha,进行了长期监测(2003—2019年冬季),并结合相关文献,评估其种群变化趋势、幼鸟比例和死亡率。研究结果如下：(1)2005—2019年3种水鸟(豆雁、灰雁和灰鹤)的种群数量呈上升趋势,7种水鸟(鸿雁、白额雁、小白额雁、小天鹅、白鹤、白枕鹤和白头鹤)种群数量呈下降趋势;(2)种群趋势下降组(N=7)和上升组(N=3)的幼鸟比例均值在2016—2...     

Kappa-chain constant-region gene sequences in genus Rattus: coding regions are diverging more rapidly than noncoding regions

We have determined the nucleotide sequence of a 1,200-base pair (bp) genomic fragment that includes the kappa-chain constant-region gene (C kappa) from two species of native Australian rodents, Rattus leucopus cooktownensis and Rattus colletti. Comparison of these sequences with each other and with other rodent C kappa genes shows three surprising features. First, the coding regions are diverging at a rate severalfold higher than that of the nearby noncoding regions. Second, replacement changes within the coding region are accumulating at a rate at least as great as that of silent changes. Third, most of the amino acid replacements are localized in one region of the C kappa domain--namely, the carboxy-terminal "bends" in the alpha-carbon backbone. These three features have previously been described from comparisons of the two allelic forms of C kappa genes in R. norvegicus. These data imply the existence of considerable evolutionary constraints on the noncoding regions (based on as yet undetermined functions) or powerful positive selection to diversify a portion of the constant-region domain (whose physiological significance is not known). These surprising features of C kappa evolution appear to be characteristic only of closely related C kappa genes, since comparison of rodent with human sequences shows the expected greater conservation of coding regions, as well as a predominance of silent nucleotide substitutions within the coding regions.      

Growth of a Molecular Base for Feeding: The Mind Body Dualism

It is often difficult to identify the ‘who, when, and where’ of advances in medicine and surgery because it's a rare advance indeed (such as the use of digitalis by William Withering) that can be clearly related to the astuteness of one person at one time and place.     

A Hidden Markov Model approach to variation among sites in rate of evolution

The method of Hidden Markov Models is used to allow for unequal and unknown evolutionary rates at different sites in molecular sequences. Rates of evolution at different sites are assumed to be drawn from a set of possible rates, with a finite number of possibilities. The overall likelihood of phylogeny is calculated as a sum of terms, each term being the probability of the data given a particular assignment of rates to sites, times the prior probability of that particular combination of rates. The probabilities of different rate combinations are specified by a stationary Markov chain that assigns rate categories to sites. While there will be a very large number of possible ways of assigning rates to sites, a simple recursive algorithm allows the contributions to the likelihood from all possible combinations of rates to be summed, in a time proportional to the number of different rates at a single site. Thus with three rates, the effort involved is no greater than three times that for a single rate. This "Hidden Markov Model" method allows for rates to differ between sites and for correlations between the rates of neighboring sites. By summing over all possibilities it does not require us to know the rates at individual sites. However, it does not allow for correlation of rates at nonadjacent sites, nor does it allow for a continuous distribution of rates over sites. It is shown how to use the Newton-Raphson method to estimate branch lengths of a phylogeny and to infer from a phylogeny what assignment of rates to sites has the largest posterior probability. An example is given using beta-hemoglobin DNA sequences in eight mammal species; the regions of high and low evolutionary rates are inferred and also the average length of patches of similar rates.